fCraft.PrepareParametrizedManifold.CheckParamVar C# (CSharp) Method

        private static void CheckParamVar( string s )
        {
            if ( string.IsNullOrWhiteSpace( s ) || ( s != "t" && s != "u" && s != "v" ) )
                throw new ArgumentException( "expected parametrization variable name is t, u, or v" );
        }